Harry Potter and the Order of the Phoenix video game question?

I'm at the point where you have to help fellow students with homework and what not to get them to come to the room of requirement. I'm in the middle of helping a boy i think by the name of Ernie. I put the cloak on and went to the potions storeroom and got the potion he asked for, but i forgot where he was. Anybody have any clue what room Ernie is in?